1. Field of the Invention
The present invention relates to a display panel and manufacturing process thereof. More particularly, the present invention relates to a photo spacer in a liquid crystal display panel (LCD panel) and manufacturing process thereof.
2. Description of Related Art
In recent years, with the highly advancing of optoelectronics and semiconductor technology, the planar display apparatuses are developed rapidly. Among several types of planar display apparatuses, a liquid crystal display apparatus is widely utilized due to their advantages such as higher display quality, higher space utilization, lower power consumption and lower radiation. The liquid crystal display apparatus traditionally comprises a liquid crystal display panel (LCD panel) and a backlight module, wherein the backlight module can provide the LCD panel with a light source.
FIGS. 1A and 1B are cross-sectional views of a conventional LCD panel. Referring to FIGS. 1A and 1B, the conventional LCD panel 100 is made of a color filter (CF) substrate 10, an active device matrix substrate 120 and a liquid crystal layer 130 disposed between the two substrates 110 and 120, wherein a color filter array layer (not shown) is disposed on the CF substrate 110 to display full colors for the LCD panel 100. A plurality of scan lines (not shown), data lines (not shown) and TFT transistors (not shown) are disposed on the active device matrix substrate 120, wherein the active device matrix substrate 120 is divided into a plurality of pixel areas (not shown) via the scan lines and the data lines. The TFT transistors are disposed in the pixel areas and are driven by the scan lines and the data lines.
It should be noted that a uniform cell gap d between the CF substrate 110 and the active device matrix substrate 120 is desired to show better display quality of the LCD panel 100. Traditionally, a plurality of photo spacers 140a or ball-type beads 140b are disposed between the two substrates 110 and 120 to keep a uniform cell gap d between the two substrates 110 and 120.
Referring to FIGS. 1A and 1B, the two substrates 110 and 120 are assembled by bonding process. During the bonding process, the photo spacers 140a or the ball-type beads 140b are pressed to be shrunk. Once the outside atmospheric pressure is lowered, the photo spacers 140a or the ball-type beads 140b expand rapidly, such that the cell gap d between the two substrates 110 and 120 increases. When the cell gap d between the two substrates 110 and 120 increases, gas will enter a space between the two substrates 110 and 120 and a plurality of bubbles occur between the two substrates 110 and 120. The bubbles occurred between the two substrates 110 and 120 deteriorates the display quality of the LCD panel 100.